Performance of the regression ABC estimator of bottleneck parameters. Parameters were estimated from the modes of posterior distributions from one thousand random samples from the prior model used for inference in Figure 1. Because each data set is a random sample from a distribution of parameters, the distribution of each estimator is divided by the true value, such that the distribution of an unbiased estimator would have a mean of one. A vertical line is placed at the mean of each distribution. The parameters are the same as in Figure 1. As in Figure 1, the tolerance was set to accept 103 draws from the prior, and the tangent transformation was used prior to regression .